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CE2204 - Surveying– I Two Mark with Answers

Anna University

CE 2204 – SURVEYING-I

Question Bank with answers

UNIT I

INDRODUCTION AND CHAIN SURVEYING

1. Define Surveying. What are the fundamental principles of surveying?

Surveying is an art of determining the relative positions of various points on, above or below the surface of the earth by means of direct or indirect measurement of distance, direction and elevation.

The principles of surveying are:

(i). Working from whole to part.

(ii). To locate a new station by at least two measurements (angular, linear) from fixed reference points.

2. What is the object or purpose of surveying?

The primary object of surveying is to prepare a plan or map to show the relative position of the objects on the surface of the earth. It is also used to determine the areas, volumes and other related quantities.

3. Name the different ways of classification of surveys.

a. Primary classification

(i). Plane surveying

(ii). Geodetic surveying.

b. Secondary classification

(i). Based on instruments used

(ii). Based on methods.

(iii). Based on object

(iv). Based on nature of the field

4. Differentiate between plane and geodetic surveying.

Sl.No.

Plane surveying

Geodetic surveying.

1.

The curvature of the earth is

The curvature of the earth is taken.

.

2.

A line joining any two points is

A line joining any two points is

considered straight.

considered as curved line.

3.

The triangle formed by any three

The triangle formed by any three

points is considered as plane

points is considered as spherical

triangle.

triangle.

4.

It is done on a area less than 250

It is done on a area greater than 250

Km 2

Km 2

5. Classify surveying based on the equipments.

1. Chain surveying

2. Compass surveying

3. Plane table surveying

4. Theodolite surveying

5. Tacheometric surveying

6. Photogram metric surveying

7. Aerial surveying

6. Explain the constructions of a diagonal scale.

For a given short length ( PQ=PR), draw a right angle triangle. Its base( PR) and height (PQ) are equal. A short length is divided into a number of parts by using the principle of similar triangles in which like sides are proportional.

Thus,

1-1 represents 1/ 10 PQ

9-9 represents 9/ 10 PQ

7. Define chain surveying. What is the fundamental principle of chain surveying?

Chain surveying is the type of surveying in which only linear measurements are made in the field.

8.What is a well-conditioned triangle? What is its specific advantage? .

A said to be well- conditioned or well proportioned when it

9. What are the operations involved in chain survey?

(i). Ranging: The process of locating intermediate points on a straight line between two end points in a straight line.

(ii). Chaining: The process of measuring the distance with a chain or tape.

(iii). Offsetting: The process of measuring the lateral distance of the object from the survey line to the left or right according to their positions.

Main station is a prominent point on the chain line and can be either at

the beginning of the chain line or at the end or along the boundary.

(b). Subsidiary stations:

The stations located on the main survey lines are known as Subsidiary

stations.

(c). Tie stations:

These are also subsidiary stations taken on the main survey lines to locate

the details of the object.

14. Distinguish between a check line and a tie line.

Sl.No

Check line

Tie line

1.

Check lines or Proof lines are the

The main object of running a tie line

lines which are run in the field to

is to take the details of the objects.

check the accuracy of the work

2.

The length of the check line

Tie line is a line which joints

measured in the field must agree

subsidiary stations or tie stations on

with its length of the plan.

the main line.

15. What are the instruments used for setting out right angles to a chain line?

(i). Cross staff.

a. Open cross staff

b. French cross staff

c. Adjustable cross staff (ii). Optical square.

(iii). Prism square (iv). Site square.

16. What are offsets? Classify them.

An offset is the lateral distance of an object or ground feature measured from a survey line. The two types of offsets are,

(i). Perpendicular offset: The angle of offset from a point on a chain line is 900.

(ii). Oblique offset: When the angle of offset is other than 900 .

Perpendicular offsetOblique offset

17. What is the use of a line Ranger?

The line Ranger is a small reflecting instrument used for fixing com intermediate points on the chain lines. Without going to either end, we can fix the intermediate . points.

18. What are the stages of fieldwork in chain surveying? Or What are the steps involved in chain survey?

1.

Reconnaissance: It is the preliminary inspection of the area to be surveyed.

2.

Marking and fixing Survey lines.

3.

Running survey lines.

4.

Taking Offsets.

19. What are the different ape corrections?

1.

Correction for absolute length or standardisation.

2.

Correction for temperature.

3.

Correction for pull or tension.

4. Correction for sag. (- ve)

5.

Correction for slope. (- ve)

20. What are the errors in chaining?

(i). Compensating Errors: Which are liable to occur in either direction and tend to compensate.

(ii). Cumulative Errors: Which occur in the same direction and tend to add or subtract. It may be positive (measured lengths more than the actual length) or negative (measured lengths less than the actual length).

The line or plane passing through the geographical North Pole, South Pole and any point on the surface of the earth, is known as true meridian or geographical meridian. True meridian at a point is constant.

True bearing:

The angle between the true meridian and a survey line is known as true bearing or Azimuth of the line.

(b). Magnetic meridian . and Bearing.

Magnetic meridian :

Magnetic meridian at a point is the direction indicated by freely suspended, properly balanced and unaffected magnetic needle at that point.

Magnetic Bearing:

The angle between the magnetic meridian and a survey line is known as magnetic bearing or bearing .of the line. It changes with time.

4. What do you understand by Whole circle bearing and quadrantal bearing of a line? Magnetic Bearings are designated by Whole circle bearing system and

quadrantal bearing system.

In Whole circle bearing system (WCB), the bearing of the line is measured with magnetic north in clockwise direction. It varies from 00 to 3600.

In quadrantal bearing system (Q.B or R.B) the bearing of the line is measured eastward or westward from north or south, whichever is nearer. The directions can be either clockwise or anticlockwise. It varies from 00 to 900.

9. The fore bearing of line AB is 155025’20”. Identify the back bearing of the line AB in

quadrantal system.

The fore bearing of line AB = 155025’20”. The back bearing of line AB , BB = FB + 180 0

= 155025’20” + 180 0

= 335025’20” (WCB)

= N (3600 – 335025’20”) W

= N 24034’ 40’’ W

10. Define and distinguish between magnetic dip and magnetic declination.

Magnetic dip:

Due to the magnetic influence of the earth, the needle does not remain in the balanced position. This inclination of the needle with the horizontal is known as the dipof the magnetic needle. To balance the dip of the needle, a rider (brass or silvercoil) is provided along with it. .

Magnetic declination:

The magnetic meridian of a place is variable one due to some local attractive forces. Therefore, the true meridian and the magnetic meridian at a place do not coincide.

The horizontal angle between the magnetic meridian and the true meridian is known as magnetic declination.

11. The magnetic bearing . of a line is 48024’. Calculate the true bearing if the magnetic declinations are 5038’ East and 50 38’ West.

True bearing = Magnetic bearing + Eastern magnetic declination

= 48024’ + 5038’ = 54002’.

True bearing = Magnetic bearing - Western magnetic declination

= 48024’ - 5038’

= 42046’.

13. The magnetic bearing of a line is S 28030’ E. Calculate the true bearing if the magnetic declinations are 5038’ East and 50 38’ West.

15. What is plane table surveying? When is it preferred? Write its principle.

Plane tabling is the graphical method of surveying in which the field

observations and plotting proceed simultaneously.

It is mainly suitable for filling the interior details between the control stations

and also in magnetic areas.

The

main principle of plane table

surveying is that the lines joining

the

points on the plane table are made to lie parallel to the corresponding lines joining the points on the ground while working at each station.

16. Name four methods of plane surveying.

1. Radiation

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2. Intersection.

3. Traversing

4. Resection.

(i). Resection after orientation by compass.

(ii). Resection after orientation by back sighting.

(iii). Resection after orientation by three point problem.

a. Mechanical method.(Tracing paper method)

b. Graphical method. ( Bessel’s method)

c. Lehman’s method. (Trial and error method) (iv). Resection after orientation by two point problem

17. When a three- point problem resorted to in plane table surveying?

It is the method of orientation when the table occupies a position not yet located on the drawing sheet.

This method is employed when during surveying the surveyor feels that some important details can be plotted easily by choosing any stations.

18. State the First and second Lehman’s rule.

First rule: The distance of the point “p” (position of plane table on the

drawing sheet) to be fixed from each rays Aa (paper a, to ground A),

Bb (paper ,b to

ground B) and Cc (paper c, to ground C) is proportional to the respective.distancescomof the

stations A, B and C from the ground station P.

Second rule: While looking towards the stations the point “p” to be fixed, will

be either to the left or to the right of each of the rays.

19. What are the Advantages of plane table surveying?

1.

It is usefulin magnetic areas.

2.

It is cheaper than the theodolite surveying.

3.

It is most suitable for small-scale maps.

4.

The surveyor can compare plotted work with the actual features.

20. Name some of the errors in plane tabling.

1.

Instrumental error.

2.

Errors of plotting

3.

Errors due to manipulation and sighting.

1.

Non horizontality of the board.

2.

Defective sighting.

3.

Defective orientation.

4.

Movement of board between sights.

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UNIT III

LEVELLING AND APPLICATIONS

1. Define Levelling. What are the uses of leveling?

Levelling is a branch of surveying, the object of which is; (i). To find the elevations of given points with respect to a given or assumed datum, and (ii). To establish points at a given elevation or at different elevations with respect to a given or assumed datum.

2. Define benchmark and reduced level. Benchmark:

Benchmark is a relatively permanent point of reference whose elevation with respect to some assumed datum is known.

Reduced level or Elevation:

The vertical distance of a point above or below the datum is known as the elevation or R.L of that point. R.L of a point may be positive or negative according as the point is above or below the datum.

3. What are the different kinds of bench marks?

A BM is the reference point of known elevation. It may be classified into

(i).G.T.S Bench Mark: The great trigonometrical survey (G.T.S) benchmarks are established by the survey of India throughout the country. The levels of this

bench marks are established very accurately at a large interval with respect to the mean sea level at Bombay port.

(ii). Permanent. Bench Mark: These are established by different Governmentdepartments like PWD, Railways, Irrigation etc,. The RL of these points are determined

(iii).Temporary Bench Mark: These are established temporarily whenever required. These are generally chosen to close the day’s work and to start the next days. Points on roofs, walls, basements, etc,.

(iv). Arbitrary Bench Mark: When the RL of some fixed points are assumed, they are termed arbitrary benchmark.

4. What do you mean by datum surface?

It is any surface, to which elevations are taken as a reference for the determination of elevations of various points. In India the datum adopted for the great trigonometrical survey (G.T.S) is the mean sea level at Bombay port.

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5. What is mean by line of collimation and height of collimation?

Line of collimation (Line of sight): It is an imaginary line passing through theintersection of the cross hairs at the diaphragm and the optical centre of the object glass and its continuation.

Height of collimation(HOC): The elevation of the Line of collimation (Line of sight) isknown as Height of collimation. HOC = RL of BM + BS.